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(let [v [1 2 3]] (match [v] [[1 1 1]] :a0 [[1 _ 1]] :a1 [[1 2 _]] :a2)) ;; _ is used for wildcard matching ;=> :a2

(match [['asymbol]] [['asymbol]] :success) ;=> :success

C++11 NOTE: std::auto_ptr has been deprecated in C++11 and will be removed in C++17. You should only use this if you are forced to use C++03 or earlier and are willing to be careful. It is recommended to move to unique_ptr in combination with std::move to replace std::auto_ptr behavior. Before we ...

int a = 5; // 0101b (0x05) int b = 12; // 1100b (0x0C) int c = a | b; // 1101b (0x0D) std::cout << "a = " << a << ", b = " << b << ", c = " << c << std::endl; Output a = 5, b = 12, c = 13 Why A bit wise OR o...

int a = 5; // 0101b (0x05) int b = 9; // 1001b (0x09) int c = a ^ b; // 1100b (0x0C) std::cout << "a = " << a << ", b = " << b << ", c = " << c << std::endl; Output a = 5, b = 9, c = 12 Why A bit wise XOR (...

unsigned char a = 234; // 1110 1010b (0xEA) unsigned char b = ~a; // 0001 0101b (0x15) std::cout << "a = " << static_cast<int>(a) << ", b = " << static_cast<int>(b) << std::endl; Output a = 234, b = 21 Why A b...

Introduction The GNU Make (styled make) is a program dedicated to the automation of executing shell commands. GNU Make is one specific program that falls under the Make family. Make remains popular among Unix-like and POSIX-like operating systems, including those derived from the Linux kernel, Mac ...

The Windows API is provided by means of a C-callable interface. Success or failure of an API call is reported strictly through return values. Exceptions aren't part of the documented contract (although some API implementations can raise SEH exceptions, e.g. when passing a read-only lpCommandLine arg...

Some API calls return a single failure/success flag, without any additional information (e.g. GetObject): if ( GetObjectW( obj, 0, NULL ) == 0 ) { // Failure: no additional information available. }

In addition to a failure/success return value, some API calls also set the last error on failure (e.g. CreateWindow). The documentation usually contains the following standard wording for this case: If the function succeeds, the return value is <API-specific success value>. If the function...

Some API calls can succeed or fail in more than one way. The APIs commonly return additional information for both successful invocations as well as errors (e.g. CreateMutex). if ( CreateMutexW( NULL, TRUE, L"Global\\MyNamedMutex" ) == NULL ) { // Failure: get additional information. ...

HRESULTs are numeric 32-bit values, where bits or bit ranges encode well-defined information. The MSB is a failure/success flag, with the remaining bits storing additional information. Failure or success can be determined using the FAILED or SUCCEEDED macros. HRESULTs are commonly used with COM, but...

When implementing SFINAE using std::enable_if, it is often useful to have access to helper templates that determines if a given type T matches a set of criteria. To help us with that, the standard already provides two types analog to true and false which are std::true_type and std::false_type. The...

Add the following code (known as the "JavaScript tracking snippet") to your site's templates. The code should be added before the closing tag, and the string 'UA-XXXXX-Y' should be replaced with the property ID (also called the "tracking ID") of the Google Analytics property yo...

The . operator in Rust comes with a lot of magic! When you use ., the compiler will insert as many *s (dereferencing operations) necessary to find the method down the deref "tree". As this happens at compile time, there is no runtime cost of finding the method. let mut name: String = &quo...

CSS body { counter-reset: item-counter; } .item { counter-increment: item-counter; } .item:before { content: counter(item-counter, upper-roman) ". "; /* by specifying the upper-roman as style the output would be in roman numbers */ } HTML <div class='item'>Item...

CSS body { counter-reset: item-counter; /* create the counter */ } .item { counter-increment: item-counter; /* increment the counter every time an element with class "item" is encountered */ } .item-header:before { content: counter(item-counter) ". "; /* print the v...

In Drupal 7 and lower, your configuration is probably stored using the Features module. To update a feature with changes from the databases use this command: drush features-update [feature-name] // e.g. drush features-update content_type_news You can also use this shorthand: drush fu [feature-n...

function createNewFolderInGoogleDrive(folderName) { return DriveApp.createFolder(folderName); } Use function createNewFolderInGoogleDrive to create folder named Test folder in a Google Drive root: var newFolder = createNewFolderInGoogleDrive('Test folder'); newFolder has Class Folder typ...

A HTTP 500 Internal Server Error is a general message meaning that the server encountered something unexpected. Applications (or the overarching web server) should use a 500 when there's an error processing the request - i.e. an exception is thrown, or a condition of the resource prevents the proces...